Explosive shell for powder actuated tool



March 16, 1965 w. F. BROSKE 3,173,359

EXPLOSIVE SHELL FOR POWDER ACTUATED TOOL Filed Nov. 23, 1962 2Sheets-Sheet l Ii [III i: 1o 4 -P,

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4%, Wm r/a March 16, 1965 w. F. BROSKE 3,173,369

EXPLOSIVE SHELL FOR POWDER ACTUATED TOOL.

Filed Nov. 23, 1962 2 Sheets-Sheet 2 INVENTOR.

(J man F. BROSKE United StateshPatent Ofitice 3,173,369 Patented Mar.16, 1965 3,173,369 EXPLOSIVE SHELL FOR POWDER ACTUATED TOOL William F.Broske, Camp Hill, Pa-, assignor to AMP Incorporated, Harrisburg, Pa.Filed Nov. 23, 1962, Ser. No. 239,618 2 Claims. (Cl. 10238) Thisapplication constitutes a continuation-in-part of my prior application,Serial No. 206,768, filed July 2, 1962, now abandoned.

In the use of powder-actuated tools for industrial purposes, it has beendiscovered that a plastic shell having a plastic plug and an explosivecharge may be utilized to retain the high combustion gases within theshell during the firing cycle, as described in my'prior application,Serial No. 793,814, filed February 17, 1959, now Patent No. 3,007,409.

This type of shell has been found particularly useful in devices forpressure-forming electrical connectors onto conductors, as described ina prior application, Serial No. 172,183, filed February 9, 1962.However, in industrial tools of the type described, it has been foundthat the presence of a grease or a lubricant on the outer surface of theplastic shell may tend to cause the shell to rupture during the firingcycle. It has not been completely established why this result occursunder these conditions, but it may be that the ungreased shell isfrictionally constrained from outward flow by the chamber of the barrel.The presence of grease or lubricant may reduce this frictionalconstraint, thus permitting sufiicient extrusion of the plastic to causerupture.

Whatever the reasons, I have discovered that if the outer surface of theshell is tapered so that the crosssection is thicker at the base andthinner at the open end, and the firing chamber is similarly tapered,rupture of the shell is prevented even when the shell is coated withgrease.

One embodiment of a shell made according to the teaching of theinvention includes a tapered shell having fluted ribs on the outersurface to effect the taper. This reduces the amount of materialrequired to make the shell, as well as dissipating the shock wave of theexplosion.

Thus, it is an object of this invention to provide a plastic shell ofthe type described, which will not rupture during firing even thoughcoated with grease. It is also an object of this invention to preventthe shell from rupturing during the firing cycle by tapering thethickness of the shell in cross-section. I have also discovered thatproviding a tapered shell to fit into a tapered firing chamber increasesthe facility with which the shell may be removed. This is particularlytrue in industrial tools where the plastic shell may be expanded duringthe operation of the tool.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there are shown and described illustrative embodiments of theinvention; it is to be understood, however, that these embodiments arenot intended to be exhaustive nor limiting of th e invention but aregiven for purposes of illustration in order that others skilled in theart may fully understand the invention and the principles thereof andthe manner of applying it in practical use so that they may modify it invarious forms, each as may be best suited to the conditions of aparticular use.

In the drawings:

FIGURE 1 is a perspective view, partially cut away, illustrating oneembodiment of the invention;

FIGURE 2 is a cross-sectional View taken along plane 22 of FIGURE 1;

FIGURE 3 is a sectional view taken along plane 33 of FIGURE 1;

FIGURE 4 is a fragmentary view showing the device of FIGURE 1 fitted ina firing chamber of an industrial tool;

FIGURE 5 is a perspective view of another embodiment of the deviceincorporating the principles of the invention;

FIGURE 6 is a view taken along plane 6-6 of FIG- URE 5; and

FIGURE 7 is a sectional view taken through plane 77 of FIGURE 6.

One embodiment of the invention (FIGURE 1), the shell casing, generallydesignated C, includes a base member 10 which is in the form of a diskclosing off one end of a cylindrical member 12. The disk 10 and cylinder12 may be integral. The preferred embodiment is achieved by molding thecasing from polyethylene. The disk 10 has a flange 14 projecting outsidethe surface of the cylinder to permit the shell to be retained in atool.

Also, as shown in FIGURE 1, the inner surface 16 of the casing C has aconstant internal diameter. The outer surface has a larger externaldiameter at the base portion 18 than at the nose portion 20. Thus theouter surface provides a tapered, frusto-conical configuration. As shownin FIGURES 2 and 3, the thickness of the cas ing in the base portion 18is greater than the thickness of the casing at the nose portion 20.

In addition to the casing, the shell comprises a plug 22 (preferably ofpolyethylene) which has an outside diameter forming a friction-fit withthe inside surface of the casing 16. The plug 22 has a primer 24 on itsexterior surface, a central axial opening 26, and a circular aperture28. When the shell is assembled (as shown in FIG- URE 1), an explosivecharge 30 is located within the easing adjacent the inner surface of thedisk 10 and retained in place by plug 22.

As shown in FIGURE 4, the shell is adapted to fit into a firing chamber40 of an industrial tool (e.g., as shown in the prior application,Serial No. 172,183, filed February 9, 1962), having a cap 44 secured tothe end thereof, and a ram 46 adapted to fit into the cylindrical shell.A firing pin 48 on one end of the ram is adapted to strike the primer 24to actuate the powder charge.

As shown in FIGURE 4, the firing chamber 40 has an inner tapered surface50 which corresponds to the taper on the outer surface of the casing C.When the ram 46 is driven against the primer 24, the primer explodes toignite the powder charge 30. The powder charge 30 drives the plug 22toward the nose portion 20 of the casing C, and thus drives the ram 46ahead of it to operate the device.

A pin 52 may be located in the cap 44 to release combustion gases, asdescribed in my prior application, Serial No. 164,756, filed January 8,1962.

Another embodiment of the invention, as shown in FIGURES 5-7, includes acasing C with a base member 10' closing one end of the cylinder 12. Thedisk 10' also has a plane 14' having an inner surface 16' of a constantinternal diameter. As shown in FIGURES 6 and 7, the tapered outersurface comprises a plurality of ribs 18' which provide a fluted orscalloped cross-sectional configuration. The ribs 18' taper from thebase 10' toward the nose portion 20 of the casing C, at which point theyblend into the outer surface of the cylinder 12'. As shown in FIGURE 6,the thickness of the cylindrical member 12' is constant when measured atthe low point between the ribs 18'. However, when the thickness ismeasured across the ribs 18', the exterior surfaces of the d ribsconverge from a maximum thickness at the base 10 to a minimum thicknessat the nose portion 20.

The shell, shown in FIGURES 57, also comprises a plug 22', with a primer24, and axial opening 26', circular apertures 28' and an explosivecharge 30' all assembled in the same fashion as disclosed in theembodiment of FIGURES 1-3. The casing C may be inserted into a tool andfired in the same manner as illustrated in FIGURE 4.

Changes in construction will occur to those skilled in the art andvarious apparently different modifications and embodiments may be madewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only. The actual scope of the invention is intended tobe defined in the following claims when viewed in their properperspective against the prior art. 1

I claim:

1. A shell casing for an explosively-operated tool comprising: a hollow,generally cylindrical member having an internal surface and an externalsurface, said internal surface having a constant diameter, said externalsurface defining a frusto-conical configuration and including a seriesof circumferential ribs, a Wall member closing one end of saidcylindrical member, the other end of said cylindrical member being open,said cylindrical member being integrally formed of plastic material,each of said ribs tapering from a major thickness proximate to the oneend of the cylindrical member to a minor thickness remote from the oneend, an explosive charge in said cylindrical member adjacent the oneend, a plug in said cylindrical member retaining said explosive chargein place, a surface of said plug facing the open end of the cylindricalmember, and means in said plug for igniting said explosive charge.

2. A casing according to claim 1 wherein the thickness of thecylindrical member between the ribs is constant.

References Cited in the file of this patent UNITED STATES PATENTS1,233,071 Lindquist July 10, 1917 1,940,657 Woodford Dec. 19, 19332,953,990 Miller Sept. 27, 1960 3,007,409 Broske Nov. 7, 1961 FOREIGNPATENTS 884,934 Great Britain Dec. 20, 1961

1. A SHELL CASING FOR AN EXPLOSIVELY-OPERATED TOOL COMPRISING: A HOLLOW,GENERALLY CYLINDRICAL MEMBER HAVING AN INTERNAL SURFACE AND AN EXTERNALSURFACE, SAID INTERNAL SURFACE HAVING A CONSTANT DIAMETER, SAID EXTERNALSURFACE DEFINING A FRUSTO-CONICAL CONFIGURATION AND INCLUDING A SERIESOF CIRCUMFERENTIAL RIBS, A WALL MEMBER CLOSING ONE END OF SAIDCYLINDRICAL MEMBER, THE OTHER END OF SAID CYLINDRICAL MEMBER BEING OPEN,SAID CYLINDRICAL MEMBER BEING INTEGRALLY FORMED OF PLASTIC MATERIAL,EACH OF SAID RIBS TAPERING FROM A MAJOR THICKNESS PROXIMATE TO THE ONEEND